Here is another trick which apparently calls for mind reading. The performer’s assistant is sent out of the room. Now, a sum of figures in addition is placed on the slate by a spectator. When he has concluded, the performer takes the chalk and draws a line under the numbers, turns the slate downward on a table, so nothing can be seen, places chalk on the slate, and retires into a corner of the room. His assistant is now called into the room, steps up to the table and seizes the chalk and marks down the correct answer to the sum of figures which is on the other side. Like all the tricks that appear the most incomprehensible, this is one of the most simple. The performer stands watching the person as he places down the numbers on the slate, he mentally adds them, and, with his hands behind his back or under his coat-tails, with a lead pencil in one hand, he writes on a piece of chalk held in the other hand the correct answer. It is needless to say that it is this piece of chalk he places on the slate, and not the one used. The chalk is scraped or filed flat a trifle lengthwise. This is to keep it from rolling on the slate, thus avoiding accidental exposure of the writing on it, and also give it a flat surface to write on. Here is an effect I produced as a stage illusion some years ago, somewhat resembling a spiritualistic effect. Hanging up against the scene, at the rear of the stage, was a large blackboard. On this blackboard writing appeared gradually, done in chalk, as though some unseen hand were actually at work. The blackboard was really nothing but fine wire slate-colored netting. There was a large hole cut in the scene immediately behind the blackboard. This hole was completely boxed in by curtains or woodwork, so as to make it as dark as night. A man was in this space, and he was dressed in a complete suit of black; also a black mask and gloves. He was provided with a pot of white paint, composed of whiting, water and glue, and a brush. Now, the man can see through this netting, but the spectators are unable to see him behind this screen of netting. With the brush and paint he traces on the wire netting whatever is desired. The paint comes through the meshes of the netting, and, adhering to it, makes a very good imitation of a chalk mark. It should be remembered the person doing the writing does so backward; so it will be in correct position when seen by the audience. [Illustration: Fig. 21.--The Board Facing the Audience.]